Hand-held flexible line trimmers are light tools used for maintenance of lawns. Lawns regular in height and uniformly trimmed are desirable in today's society. Presently, in order to achieve the quality yard desired, several pieces of yard equipment must be employed, i.e., mowers, edgers, trimmers, etc. No single machine capable of performing all yard functions exists on the market today. Current machinery has existed without substantial design change for a substantial period of time, thus inferring that with regard to basic lawn equipment optimal designs have been reached. Consequently, a need exists for adapting or converting existing designs so as to perform several lawn maintenance functions, thereby minimizing the need for several pieces of lawn equipment and thus reducing cost of maintenance for the general home owning public.
Gas powered and electric-powered flexible line trimmers vary greatly in overall design and use. Electric trimmers, as shown in my prior U.S. Pat. No. 4,712,363, have a trimmer head incorporating a relatively heavy electric drive motor and housing. The weight of the electric-powered trimmer is concentrated at the head. Gas powered trimmers, in contrast, have the gas engine mounted at the end of a boom opposite the trimmer head, with the carrying handles located at approximately the balance point.
Further, the prior art includes the device shown in U.S Pat. No. 4,512,143 to Jimenez. Jimenez teaches a carriage for line trimmers having a frame resting on tubular runners which act as skids. The trimmer attaches to the frame and the skids provide a reference to the ground providing a uniform cutting path height for mowing a lawn.
Complete pieces of lawn equipment are taught by U.S. Pat. No. 4,364,435 to Tuggle et al. and U.S. Pat. No. 4,205,439 to Sweet. These patents teach a motor and handle, with a boom attached thereto supporting a head assembly having a cutting element. In each of these patents, the motor drives the cutting element through the boom.
The prior art also teaches dollies for converting flexible line trimmers for use as mowers and edgers. In particular, U.S. Pat. No. 4,442,659 to Enbusk teaches a dolly having a pair of wheels supporting a handle and pivotal mount to which the trimmer boom is attached. The mount pivots reacting to the control of the user as the operator moves the dolly forward. The operator controls orientation of the cutting path, consequently several degrees of freedom must be maintained by the operator, and thus, the desired uniform cutting path is difficult if not impossible to achieve. U.S. Pat. No. 4,182,100 to Letter teaches a elaborate three-wheeled frame on which the line trimmer rests. In Letter's initial configuration the trimmer acts as a mower. Further, the trimmer is attached to a pivoting handlebar and the extended trimmer boom attaches to the front of the frame. By applying pressure to the handlebars the trimmer may be rotated so as to provide a lawn edging cutting path. Once again, a multiple degree of freedom system necessitates that an inordinate amount of control to be exercised by the operator in order to maintain a uniform lawn edge.
Prior art also teaches a configuration for converting an electric power saw for use as a lawn edger. U.S. Pat. No. 3,587,749 to Sauer teaches a wheeled carriage and handle to which the power saw is attached. The blade of the power saw extends to one suitable for lawn edging.
The prior art further teaches a conversion device for attachment to a line trimmer. U.S. Pat. No. 4,224,784 to Hansen et al. teaches a device with two legs forming a triangular frame extending and providing axes for two wheels. The frame is attachable to the line trimmer by means of a mounting collar, but is configured to fit line trimmers having only specific dimensions. Hansen's device lacks universality, a highly advantageous feature for a device intended for use with pre-existing line trimmers.
Finally, my U.S. Pat. No. 4,712,363 discloses a two-wheeled apparatus for converting a flexible line trimmer for use as a lawn edger. My prior invention is optimal when used in conjunction with an electric trimmer, where the weight of the tool is concentrated at the head and the enhanced support and stability of two wheels are required. I have found, however, that the added complexity and cost required for the device is not optimal when used in conjunction with a gas-powered trimmer.
Consequently, a need presently exists for an attachable conversion apparatus which optimally will be utilizable with gas-powered flexible line trimmers. The apparatus will be lightweight and adapted to allow use of the trimmer in either a near-vertical or a horizontal mode without removing the apparatus. Finally, the apparatus should provide for trimming in a plane tilted away from the operator to remove the nuisance and hazard of flying debris.